most do not want the Republic of Ireland to take over N Ireland. If the minority there do not want to be British then let them go to Ireland
The majority (nearly 60%) would like to join the Republic IF the UK closes off the border. The die-hard republicans are probably in single digits. The die-hard unionists are also at max 20%.
If NI goes entirely to RoI, then 20% would object strongly.
hopefully the aim would be the one country two systems approach. It gives a hard brexit and keeps the irelands borderless. Win win